This invention relates to protective coatings. More particularly, this invention relates to easily removed protective membranes which adhere to and isolate vessels in such a manner as to control the migration of hazardous, toxic, radioactive or otherwise potentially troublesome materials.
There exists a significant need for the reliable confinement, safe handling, transport and disposal of hazardous materials. Of concern are those areas where attempts to clean a containment vessel holding such materials could involve a further exposure of personnel due to the unintentional spread of the materials. Prior procedures involve transport and/or storage of such materials in vessels having surfaces that are impermeable to the materials. After removal of the hazardous materials, the vessels are typically cleaned with conventional cleaning solutions.
The above procedure, however, has the disadvantage that it exposes personnel to both the contaminated surface and the cleaning solution. Furthermore, this procedure creates contaminated cleaning solutions which must be disposed of and often leaves contaminated surfaces only partially cleaned.
The present cleaning and decontamination technology is further complicated by the requirement that each crew member work in a special suit consisting of boots, rubber gloves, protective clothing, and respiratory protection equipment. That requirement results in extreme fatigue, a potential for accidents, significant cost considerations, and a loss of productivity. Decontamination under such conditions can also be a time-consuming activity that extends the time in which the vessel cannot be used.
Moreover, the routinely encountered surfaces, e.g., stainless steel, coated carbon steel, and polyethylene, do not present a tacky surface and, therefore, harmful dusts can readily become airborne if the surface becomes dry.
Additionally, the hazardous material can leak through defective welds or structural cracks in one or more surfaces defining the area holding the hazardous liquid material to contaminate unprotected surfaces, thus requiring additional decontamination processes.
Protective coatings have long been recognized as candidates for helping to control the diffusion, migration and ease of decontamination of these surfaces. However, such coatings have been limited because they either cannot easily be removed, or cannot withstand the chemical environment of the hazardous material or cleaning solution, or they loose bond and detach from surfaces during contact with the cargo. For example, U.S. Pat. No. 4,632,847 to Lomasney et al. relates to a process for using strippable coatings in the process of asbestos removal. However, the coatings of that patent, while readily removable, are not designed to withstand contact with hazardous materials which are liquid. Such coatings clearly could not perform within the operational parameters of, for example, the demineralized water in a nuclear reactor refueling pool.
Thus, it would be desirable to provide easily removable, protective coatings for protecting vessels that contain hazardous materials, which coatings could eliminate or reduce many of the above problems associated with conventional contamination confinement methodology.